Rhododendron rootstock named ‘Rhodunter 37’

ABSTRACT

A new and distinct  Rhododendron  hybrid plant used as a rootstock that exhibits hardy and vigorous growth.

Botanical classification: Rhododendron hybrid.

Varietal denomination: ‘Rhodunter 37’.

BACKGROUND OF THE INVENTION

The present invention comprises a new and distinct cultivar ofRhododendron hybrid used as a rootstock known by the varietal name‘Rhodunter 37’. The new variety was discovered in Ahrensburg, Germany.The new variety is the result of a planned breeding program between anunpatented Rhododendron fortunei (female parent)×cv. ‘Cunningham'sWhite’ (unpatented male parent). The new variety exhibits matroclinalmorphological features. ‘Rhodunter 37’ exhibits more prominent leafvenation than both parents, but is similar in leaf color and shape toboth parents. The new variety has been trial and field tested and hasbeen found to retain its distinctive characteristics and remain true totype through successive propagations.

DESCRIPTION OF THE DRAWINGS

The accompanying photographic drawings illustrate the new variety, withthe color being as nearly true as is possible with color illustrationsof this type.

FIG. 1 shows a side perspective view of a typical flowering plant of thenew variety grown to a flowering plant;

FIG. 2 shows a close-up view of the inflorescences of the new variety;

FIG. 3 illustrates the new variety with some of the flowers not open;and

FIG. 4 illustrates the new variety with nearly all of the flowers open.

DESCRIPTION OF THE PLANT

The following detailed description sets forth the characteristics of thenew cultivar. The data which defines these characteristics werecollected by asexual reproductions performed using tissue culture mediumfor shoot multiplication of Rhododendron species and which were carriedout in Ahrensburg, Germany. The color readings were taken in naturaldaylight. The field-grown plants were five years old when described(unless indicated otherwise). The soil was a sandy loam mixed with peat.Color references are primarily to The R.H.S. Colour Chart of The RoyalHorticultural Society of London.

PLANT

-   Type: Evergreen shrub.-   Use: Rootstock.-   Soil: Sandy loam.-   Light: Full.-   Fruit bearing: Very low.-   Crop time: 1.5 years is required to achieve finished product size    that is ready for use as a rootstock.-   Dimensions at crop time (3 years after grafting. Dimensions depend    on the vigor of the scion cultivar):    -   -   Height.—50 cm.        -   Length.—40 cm.-   Vigor: 120% of standard using ‘Nova Zembla’ (unpatented) as the    standard.-   Habit: Erect.-   Hardiness: USDA zone 6a.-   Rooting habit: Compact root bales.-   Time to initiate roots: 3 months at 22-25° C. for softwood cuttings.-   Disease and pest resistance: No observations made to date.-   Trunk (at 4 years):    -   -   Diameter.—3 cm.        -   Height.—5 cm above soil.        -   Bark color.—Surface: Year 1: 144A. Year 2: 144A to 175A.            Year 3: 175A. Year 4: 177B to 197B-197C. Flesh: 157B.        -   Lenticels.—Inconspicous.-   Branches:    -   -   Color.—Surface: Year 1: 144A. Year 2: 144A to 175A. Year 3:            175A. Year 4: 177B to 197B-197C. Flesh: 157B.        -   Length (at one year).—20 cm.        -   Base diameter (at one year).—7 mm.        -   Texture.—Hard.        -   Internode length.—1-2 cm.        -   Branching angle at emergence.—45° angle.        -   Habit.—Compact.        -   Pubescence.—Absent.        -   Branch lenticels.—Inconspicous.-   Leaves:    -   -   Arrangement.—Alternate.        -   Length.—13 cm maximum.        -   Width.—4 cm maximum.        -   Shape.—Oblanceolate; with the blade occasionally undulated.        -   Apex.—Truncated.        -   Base.—Triangular.        -   Color.—Adaxial: 147A. Abaxial: 147C.        -   Surface.—Adaxial: Glabrous. Abaxial: Glabrous.        -   Margins.—Entire.        -   Division.—Undivided.        -   Petiole.—Length: 2 cm. Width: 2 mm. Color: 144A. Surface:            Glabrous.        -   Leaf stipules.—Sessile.        -   Leaf pubescence.—Absent.        -   Venation pattern.—Feather-veined.        -   Vein color.—Adaxial: 144A. Abaxial: 145C.        -   Leaf texture.—Hard.        -   Leaf appearance.—Typical Rhododendron leaf.-   Fruit: Fruits (capsules) are usually absent due to self-sterility or    incompability with other Rhododendrons. When present, the seed color    is 164B.-   Flower:    -   -   Arrangement.—Single.        -   Shape.—Widely funnel-shaped.        -   Bud.—Shape: Oblong; Ellipsoid. Width: 20 mm. Length: 40 mm.            Color: Closed: 186B. Bursting: 75B. Time of bloom: At 2            years old. Lastingness of bloom: 21 days.        -   Diameter.—8 cm.        -   Depth.—20 mm.        -   Bloom quantity.—13-17 per truss.-   Petals:    -   -   Shape.—Fused; the corolla has a wide funnel shape.        -   Number.—7.        -   Length.—40-50 mm.        -   Width of corolla.—70-80 mm.        -   Apex.—Round.        -   Margin.—Slightly undulated.        -   Color.—When opened: Upper surface: 69 A to 69 D. Lower            surface: 69 A. Before bud burst: Lower surface: 73 B to 73            C.        -   Peduncle.—Length: 4 cm. Width: 3 mm. Surface: Glabrous.            Color: Green when flowers are fully open.-   Sepals: Not present.-   Petaloids: Not present.-   Natural flowering season: Beginning of May through the end of May.-   Fragrance: Inconspicuous.

REPRODUCTIVE ORGANS

-   Stamens:    -   -   Number.—14.        -   Length.—30 mm.        -   Color.—150D.-   Anthers:    -   -   Shape.—Normal Rhododendron type.        -   Color.—158B.        -   Length.—25 mm.        -   Width.—1 mm.        -   Amount of pollen.—Medium.        -   Color of pollen.—150D.        -   Stigma color.—145A.-   Pistil:    -   -   Length.—5 cm.        -   Number.—1.-   Style:    -   -   Color.—159D.        -   Length.—45 mm.        -   Width.—1 mm.-   Ovaries:    -   -   Length.—5 mm.        -   Width.—3 mm.        -   Color.—137C.        -   Position.—Superior.

1. A new and distinct variety of Rhododendron hybrid plant, asillustrated and described.